<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>demo 2-15</title>
	</head>
	<body>
	</body>
	<script>
		const s = 'welcome';
		console.log(s.trim());
		console.log(s.trimStart());
		console.log(s.trimEnd());
	</script>
</html>